Overview of H.323 471Overview of H.323 The H.323 standard provides a foundation for audio, video, and datacommunications across IP-based networks, including the Internet. Bycomplying with H.323, multimedia products and applications fromdifferent vendors can interoperate, allowing users to communicatewithout concern for compatibility.An NBX ConneXtions H.323 Gateway provides connections similar totie lines between existing NBX systems across an IP network. However, itcan also support voice connections between a 3Com Telephone andother H.323-compliant devices.ConneXtions H.323 Gateways support communication with:■ Extensions on other NBX systems that have a ConneXtions gateway.■ Extensions on PBX systems that have an attached H.323 gateway.■ H.323 gatekeepers.■ Miscellaneous H.323-compliant end-point devices such as:■ H.323 telephones.■ Suitably equipped personal computers.■ An emerging class of wireless handsets.The quality of H.323 calls over the Internet is determined by the quality ofthe connection provided by your ISP.The H.323 protocol addresses these main areas:■ Negotiated Connections■ Negotiated Voice Compression■ Standard Extensions■ Remote Internet Device ConnectionsNegotiatedConnectionsThe H.323 protocol adds negotiated call setup and tear-down capabilitiesto Internet Protocol (IP) connections. It exists because Internet protocolswere designed to deliver text messages and computer files in datapackets. IP networks were not originally concerned about involving aperson in a real-time conversation as a telephone does.H.323 provides call setup capability to negotiate the readiness of twoparties to exchange information and how they do it. It then keeps the
